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Audio1950 8th Aug 2014 8:00 pm

Another woodworm question!
I've just bought a portable gramophone from France, the case of which was riddled with worm. The seller is sending me the innards only, as I have a spare case. However, the plywood motor board he's sending me has one or two worm holes, and past posts suggest that freezing the llittle devils is effective. If so, how long would I leave it in the freezer, and would this have any effect on the highly polished walnut finish, or would it be better to use a proprietry killer like Rentokil? Anyone tried freezing a polished cabinet?


paulsherwin 8th Aug 2014 8:28 pm

Re: Another woodworm question!
I would just use lots of woodworm killer. I've never had any reinfestations when I've done this.

The trouble with the freezer approach is that it doesn't kill the eggs. There are complicated sequences of freezing and warming which you can go through to encourage all the eggs to hatch out, but you can never be certain there aren't a few eggs lurking somewhere.

David G4EBT 8th Aug 2014 10:43 pm

Re: Another woodworm question!
The holes aren't holes where the woodworm burrowed into the wood, but 'flight holes' where the 'woodworm' larvae pupated, turned into bettles and left the wood, having burrowed up and down in their long larval stage for perhaps uo to 4 years. It won't do any harm to soak it in rentokil or whatever, but the culprits will have long ceased to have been in residence. Inside, the wood will be honeycomb of course, with little strength.

paulsherwin 9th Aug 2014 1:01 am

Re: Another woodworm question!
But, the wood will be infested with eggs which will emerge as woodworm eventually and start chomping the wood. Freezing the wood kills any worms but doesn't affect the eggs much. Woodworm killer poisons the wood so the emerging worms are killed as they burrow their way through it.

brenellic2000 9th Aug 2014 10:37 am

Re: Another woodworm question!
The furniture beetle lays its egg in an attractive, secure life supporting crevice late spring/summer - they very rarely lay an egg in a flight hole, though nothing is impossible.

It is impossible to say where or when they will attack or emerge. The only certainty you have of an attack is from the fresh, fine gritty dust as they emerge from a flght hole April to June - how they know that date or how close they are to the surface is beyond me!); that is the only time that a woodworm killer has any real change of doing its job and when freezing/fumigation works best.

Pouring gallons of stuff down disused flight holes only adds to Mr Rentokil's profits! But regularly treating joints and dusty crevices is beneficial as these support the larvae's early life. You have to remember that only steeping timber in a bath of preservative over a week or so actually allows preservative to soaks into the cells by osmosis and leave sufficient insecticide to do its job as the vehicle evaporates. Brushing woodworm killer onto wood leaves only a useless trace deposit as the vehicle will have evaported long before it penetrates meaningfully into the cell wall. Poorly treated timber only gives the larva a headache and indigestion.

Treated 'woodwormed wood' is more likely not showing further signs of attack because the attack is long since gone or the environment is not attractive to the furniture beetle, which usually lives on damp wood or decaying wood.

Nature will always win over man - vigilance over attacks is the key!

Audio1950 9th Aug 2014 3:39 pm

Re: Another woodworm question!
Thanks for all the suggestions. It looks as though a thorough drenching of the motorboard over a period of days is the answer here, as well as treating the bare timber of the cabinet, just to be on the safe side!


Michael.N. 9th Aug 2014 5:48 pm

Re: Another woodworm question!
Do nothing. Place the offending wood in a dry environment and all will be fine.
Woodworm or the common furniture beetle usually emerge in Spring, March/April.

paulsherwin 9th Aug 2014 7:34 pm

Re: Another woodworm question!
It takes a brave man to do that. I've certainly had CFB emerging from plywood cabinets after several months' storage in a normal centrally heated house. Once they get established in the plywood layers they're pretty resilient, though they may not reinfest after eradication once the wood is completely dry.

G6Tanuki 9th Aug 2014 8:06 pm

Re: Another woodworm question!
Owning a 160-year-old house with *lots* of wood, I must admit to a level of conditioned paranoia about allowing woodworm-suspect timber in any form to cross my thresholds.

Woodworm don't like extremes of temperature: as others have mentioned, cold is not life-enhancing for them. Neither is heat: some years ago I was doing work on a 1930s wood-cased mantel clock that had been home to worms, and 'treated' it by raising its temperature to around 90 Centigrade over a period of days courtesy of a friend's Aga.

After slow cooling and allowing the wood to stabilise back to more-normal levels of humidity I filled the holes with a slurry-mixture of wood-flour and cellulose dope, then multiple treatments of Danish Oil restored a deep and quietly unpretentious lustre to the wood.

These days I prefer to work with metal-cased "communications" radios - at least that way I know rust won't spread to the structure of the house!

Michael.N. 9th Aug 2014 8:35 pm

Re: Another woodworm question!
Paranoid is the right word. I have thousands of pounds worth of musical instrument making wood in my workshop - from very expensive Spruce to very expensive Rosewood. I think many would be absolutely stunned just how expensive some of this stuff is.
A couple of months ago I was hand planing some highly figured Maple when I suddenly started to notice the tell tale tunnels of woodworm. This particular Maple was bought a couple of months prior to me working it. It wasn't infected in my workshop. The more I planed the more that was revealed, including some frass.
I tossed the wood into a corner of the workshop where it still remains and will do so for probably many years to come. I'm not the slightest bit worried about my expensive stock. Not one bit. My workshop is too dry for them. 35 years of experience tells me that. I won't have the chemical stuff anywhere near my wood.

paulsherwin 9th Aug 2014 9:07 pm

Re: Another woodworm question!
They particularly like mid 20th century plywood though - it's someting to do with the glue.

I'm pretty laid back about CFB infesting the house. It was fumigated 30 years ago using serious chemicals, and there's been no sign of any activity since. They aren't attracted to modern furniture and wooden surfaces sealed with polymers.

Michael.N. 9th Aug 2014 9:54 pm

Re: Another woodworm question!
Might be the glue, might be the type of wood- Birch? They really do seem to love Maple but not dry Maple. One thing I do know for sure is that they absolutely adore damp conditions. I used to house bash many years ago, damp cellars and under leaking baths was their favourite hunting ground. I even had to replace several joists in my own cellar because they had got at them - a severe infestation. It's a damp cellar and had little air circulation. I replaced the joists, put in 5 or 6 air bricks and everything has been fine since. That was over 10 years ago.
I remember removing a side bath panel for a customer and the floorboards were absolutely riddled with them. Further inspection revealed that it wasn't just the floorboards. The joists were also riddled with holes. So bad that it was a miracle that a full bath didn't land in the floor below. But it was just confined to the section under the bath, the rest of the bathroom and the other areas on that floor were perfectly fine. No evidence at all.
Probably the clue to this is how old Radios have been stored. I suspect many found their way to Cellars and outbuildings that are a little on the damp side. I know my father had dozens of old wooden radios in the attic and I can't remember ever seeing a cabinet that had woodworm.
The radios have gone but that attic space is now my workshop. I have never seen evidence of woodworm other than stuff that has been brought into the workshop. I've had active wood brought in on a number of occasions. I've even watched them exiting, seen dozens of the little blighters land on the walls. Not once have they gone on to infect my wood and there's plenty of unvarnished wood for them to go at!

brenellic2000 10th Aug 2014 10:31 am

Re: Another woodworm question!
The irony is that while timber in 'dry', warm domestic rooms is down to 9-12% MC, the drier the timber the less readily it absorbs preservatives as the dried-out outer cell walls (if not lacquered!) no longer allow transfer of preservative by the vehicle (solvent or waterborne) to readily permeate through osmosis or diffusion into the more moist inner cells.... where the larvae are probably still active.

Don't forget that seasoned timber is like a cake - baked hard and dry on the ouside but still moist in the middle. If the larvae are already present, they will emerge in due course without warning, but you are not likely to have further infestion if kept dry and well dusted, especially in crevices.

The best time to treat timber is before its moisture content drops too low (around 18-23% MC). As Michael will attest, seasoning needs a dry, well aired room/store. If you do get new timber in, make sure the sap wood has been removed as that supports life, especially pin-hole borers or wood wasps in certain specie.

As to freezing, the consensus is still out. -20C (-5F) is the recommended level, probably at the extreme of a domestic freezer. The timber/furniture should be in an air tight bag to minimise ice crysals being later absorbed which may/maynot cause warping/breakdown of glues. It is a bit hit and miss as is over heating (50C/122F) which can similarly cause structural problems - though the larvae might get a sun-tan! Don't forget the Tundra is in a deep freeze much of the year... but still bursts into verdant life in the spring (and the Sahara too), and that timber has wonderful insulation properties!! Ain't nature wonderful?!


David G4EBT 10th Aug 2014 5:59 pm

Re: Another woodworm question!
The thing to remember is that the presence of lots of holes equates to the absence of lots of beetles. The flight holes aren't where they got in, but where they came out - in the case of woody radios, probably decades ago. The beetles don't descend on wood like a swarm of locusts boring holes all over the surface of a cabinet - each infestation results from a female adult beetle discreetly laying eggs in an environment she judges suitable for her offspring - moist nutritious wood. If you have moist nutritious wood anywhere in your house then adult female beetles - flying around everywhere between April and July may lay eggs in it. If the wood is dry - as it will be if you live in a normal heated and ventilated house - they won't. The infestation in old woody radios probably happened decades ago when they were stored in damp conditions such as sheds and cellars.

Once timber is infested the insects burrow up and down for 3 - 5 years until they become adult beetles and emerge - only then is there any evidence of the infestation. When that generation has hatched out and flown, that's an end to it and it's a waste of, time, money and effort dousing a radio cabinet or any other previously infested timber with chemicals. Companies who market expensive woodworm treatments have done a rather good job at creating paranoia, just as those who market 'isotonic energy drinks' and mineral water to 're-hydrate' ourselves have convinced millions of people of the efficacy of their products.

I've heard of people who - having seen holes in a radio cabinet - have immediately put it in a sealed bag for fear that (non-existent) beetles will infest their house. Not so - they're very discerning about where they lay their eggs and if it isn't April to June they won't be laying any eggs anywhere, any more than would a bird, apart from which - in a modern house - the beetles wouldn't find any timber suitable.

The only issue with a radio cabinet isn't how to treat woodworm that don't exist, but how to make a cabinet peppered with flight holes look presentable. In my view, nothing short of re-veneering will do that, apart from which the cellular structure of the timber will be been broken down. It's instructive to split the timber lengthwise to see what's left of it, which isn't a lot. Unless it's a cherished or much sought after radio, really, it's just a donor for parts and not much use for anything else.

Nothing will change - people will believe what they want to believe and will continue to use expensive chemicals on the basis that even if it doesn't do any good, it won't do any harm, so why not give it a go? I guess it's a bit like lucky charms and homeopathic medicine - an act of faith. The dictionary defines 'faith' as 'a strong or unshakeable belief in something without proof or evidence'. Quite so.

McMurdo 10th Aug 2014 6:27 pm

Re: Another woodworm question!
SWMBO bought a holey Murphy a few months ago and injected it with woodworm killer. The following day there was a pile of dead beetles on the have been warned!

HamishBoxer 10th Aug 2014 7:06 pm

Re: Another woodworm question!
Well, it does seem the worm killer works.

richrussell 11th Aug 2014 9:26 am

Re: Another woodworm question!
I see no harm in giving anything wooden that comes into my possession with visible flight holes a good soaking in woodworm killer. If nothing else, the stuff I tend to use also acts as a wood preservative and anti-fungal. Which if it's been stored in a damp shed or garage may also be an issue.

Audio1950 11th Aug 2014 10:55 am

Re: Another woodworm question!

Originally Posted by McMurdo (Post 698747)
SWMBO bought a holey Murphy a few months ago and injected it with woodworm killer. The following day there was a pile of dead beetles on the have been warned!

This illustrates exactly what I have been thinking - just because there are flight holes, indicating that one or more generations have departed, surely that doesn't mean there are no more still happily chomping away inside?


brenellic2000 11th Aug 2014 11:04 am

Re: Another woodworm question!
Re Kevin's comment "a few months ago" (and Barry's concern) - that would be April-May about the time the adult beetles first start to break surface and fly off, leaving behind the tell-tale frass (gritty dust). That is possibly why the radio was sold!

That is only time that applying woodworm killer to the area (preferably soaking) has any immediate and real effect. The activity may last until August.

At the first sign of the tell tale dust give the timber a good thumping with a rubber mallet to dislodge dust and allow better penetration, but it won't dislodge or kill beetles about to emerge as the wood-worm killer is unlikely to penetrate the thin outer layer unless steeped.

As has been said above by those of us long working in it timber-trades, wood-worm killers are sold mostly on the basis of closing the stable door after the horse has bolted for the simple reason it is impossible to tell where and when an attack will take place.

You can pre-treat timber before use to prevent attack in interior furniture but it is not in the interests of the woodworker to breathe in treated wood dust, nor is it cost effective for manufacturers and buyers for indoor furniture, which is kept dry! The problem comes with buying second-hand furniture or not mending leaky roofs!

But there is caveat! Many British hardwoods used in furniture tend not to become suseptible to attack until 60-80 odd years old by when the timber is age hardening... it's a mystery why this is so! The furniture beetle can and will attack even in a 'dry' house, so be be vigilent of dirt-traps!

If you're worried about the chemicals - usually a nerve agent - and it is a very genuine and honest concern - nature does have a solution: pure turpentine. Its not gauranteed to kill but it discourages the beetle from laying its eggs (a bit like creosoted string warding off runny babbits on allotments).

brenellic2000 11th Aug 2014 12:49 pm

Re: Another woodworm question!
'afore I forget: if you're steeping in a solvent based insecticide (most still are), no need to worry about the timber/ply/veneers warping on drying out but make sure you do so in a well ventilated place.

If using a water borne insectidice under new EU regs, best not steep - brush or sponge on! And don't comment on homeopathy as the moderators will delete it!!

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